• Fire Science and Engineering
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• v.33 no.3
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• pp.37-43
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• 2019

In this study, ethanol pool fire extinguishing experiments were conducted using a twin-fluid nozzle. Ethanol pool fires, 5.027×10^-3 ㎡ and 1.131×10^-2 ㎡ in size (80 mm and 120 mm in fuel pan diameter, respectively), were tested, and the flow rates supplied to the twin-fluid nozzle for fire extinguishing were 156-483 g/min and 20-70 L/min for water and air, respectively. The heat release rate increased with increasing fire source area, and heat release rates of 5.027×10^-3 ㎡ and 1.131×10^-2 ㎡ in size were measured to be 1.01 kW and 5.51 kW, respectively. For both fire source cases in the present experimental range, regardless of the water flow rates, the ethanol fires were extinguished successfully under the high air flow rate condition (e.g., above 40 L/min). On the other hand, under all water flow rate conditions, the fire extinguishing time and water consumption decreased with increasing air flow rate, which were approximately 23 s and 185 g under high air flow rate conditions (e.g., above 50 L/min), respectively. Based on the water consumption per heat release rate, the present experimental data were compared with the previous ones using a single-fluid nozzle, and it was found that the twin-fluid nozzle could extinguish a fire with a lower water consumption than a single-fluid one.

• Nuclear Engineering and Technology
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• v.26 no.4
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• pp.471-483
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• 1994

A sodium fire facility with a test chamber of 1.7㎥ volume was constructed and operated to carry out experiments of sodium fires such as pool, spray, and columnar fires which might take place in sodium-related facilities. The experimental results of pool fires showed that the increase of temperature and pressure in the test chamber was much smaller than that of spray and columnar fires even though their amount of sodium injection in the chamber was much larger compared to other types of fires. And it was found in pool fires that the temperatures of sodium pool and the gas temperature in the test chamber had been maintained much longer than other types of fires, and that the chamber pressure had come to vacuum due to depletion of the oxygen for a large amount of sodium injection in the chamber. The experimental results of spray fires showed that sprayed sodium of small particles instantly reacted with oxygen, and that its reaction heat increased gas temperature and pressure of the test chamber rapidly and decreased them shortly. And the maximum gas temperature and pressure of the test chamber in spray fires ore greatly changed according to the inlet sodium temperature in the test chamber. The characteristics of the columnar fires were almost similar to those of spray fires, but the maximum temperature and pressure of the test chamber were much smaller even for a large amount of sodium injection. And it was shown in spray and columnar fires that the temperatures at each measurement position in the test chamber were quite different due to the instantaneous sodium oxidation in comparision with pool fires. Finally, the graphex powder was proved to be a very effective extinguisher against sodium pool fires.

• Tunnel and Underground Space
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• v.15 no.1 s.54
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• pp.55-60
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• 2005

In this study, the 1/20 reduced-scale experiments using Froude scaling were conducted to investigate the effect of longitudinal ventilation on the variation of burning rate in tunnel fires. The methanol square pool fires with heat release rate ranging from 3.57 kW to 10.95 kW were used. The burning rate of fuel was obtained by measured mass using load cell and temperature distribution were measured by K-type theomocouples in order to investigate smoke movement. The wind tunnel was connected with one side of the tested tunnel, and logitudinal ventilation velocity in the tested tunnel was controlled by power of the wind tunnel. In methanol fire case, the increase in ventilation velocity decreased the turning rate due to the direct cooling of fire plume. For the same dimensionless velocity(V), homing rate decreased as the size of pool fire increased.

• Fire Science and Engineering
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• v.32 no.5
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• pp.34-39
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• 2018

In this study, the experiment conditions for the variation of heat release rate in compartment space were constructed to analyze the effects of fire spread and the operation time of sprinkler in accordance with the heat loss of the sprinkler's heat element. The compartment composed of fire board (width = 0.3 m, height = 0.5 m, length = 3.0 m), are manufactured to measure the temperature distributions in the inner space, the mass loss rate and heat release rate during the experiment of N-heptane pool fire test. Also, the operation time of sprinkler is analyzed with the installation of sprinkler and C-factor using Fire Dynamics Simulator Ver.6 under the experiment conditions. The results show that the operation time of sprinkler, which has RTI $100(m{\cdot}s)^{0.5}$ operating temperature $70^{\circ}C$, is 30 s~60 s for C-factor = 0 and 1, 62 s~92 s for C-factor = 3, and 120 s over for C-factor = 5, respectively.

• Fire Science and Engineering
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• v.28 no.5
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• pp.1-7
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• 2014

The present study has been conducted to analyse the effects of various pool diameters on the measurement of heat release rate (HRR) of heptane fire using large scale cone calorimeter (LSC). The burning rate which is the major parameter for HRR compared with the previous model suggested by A. Hamins. The combustion efficiency for heptane by oxygen consumption method is about 91%, which is almost same with the previous results of 92% suggested by J. Gore. The convective HRR by enthalpy consumption method was 54% lower than HRR by oxygen consumption method. This results are practical use for establishing the reliability of heat release rate for fire experiment.

• Fire Science and Engineering
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• v.33 no.5
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• pp.28-36
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• 2019

In the present study, the effects of supply gas and water mist on the heptane pool fire extinguishing performance were investigated using the full cone and hollow cone twin-fluid atomizers. Air or nitrogen of 30 lpm (Liter per minute; L/min) was used as the supply gas, and the experiments were conducted under the water flow rate conditions of 0 lpm (i.e., discharge of air or nitrogen only) and 0.085 lpm (i.e., discharge of water mist with supply gas). Experimental results confirmed that the use of water mist discharge with the supply gas and full cone spray pattern reduced the fire extinguishing time as compared to that of only supply gas discharge and hollow cone spray pattern. In addition, for the discharge of water mist using the full cone twin-fluid atomizer, water mist significantly affected fire extinguishing performance, whereas the effect of the supply gas was less pronounced. On the other hand, for the discharge of water mist using the hollow cone twin-fluid atomizer, the fire extinguishing time was remarkably reduced by the supply of nitrogen, as compared with that of air, indicating that the supply gas as well as water mist can significantly affect fire extinguishing performance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.7
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• pp.976-982
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• 2002

In this study, smoke movement in tunnel fire with natural ventilation shaft has been investigated with various size of fire source. Gasoline pool fire with different size of diameter - 73mm, 100mm, 125mm and 154mm - was used to describe fire source. Experimental data is obtained with 1/20 model tunnel test and its results are compared with numerical results. The computation were carried out using FDS 1.0 which is a field model of fire-driven now. Temperature profiles between measured and predicted data are compared along ceiling and near the ventilation shaft. Both results are in good agreement with each other. In order to evaluating a safe egress time in tunnel fire, horizontal smoke front velocity was measured in model tunnel fire tests and those are compared with numerical results. According to the presence or absence of natural ventilation shaft, ventilation effect are estimated quantitatively. Finally, this paper shows that computational fluid dynamics(CFD) is applicable to predict fire-induced flow in tunnel.

• Fire Science and Engineering
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• v.33 no.1
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• pp.39-44
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• 2019

In this study, the relationships between the material properties of the wall and the fuel mass flux in compartment fire. The fire resistant board (fire-board) and steel plate compartments are constructed with a 0.3 m width, 0.5 m height and 3.0 m length. To obtain the mass loss rate considering the location of the fire origin in compartment, experiments of a heptane pool fire are performed with a combustion area of $0.01m^2$ and $0.0225m^2$. The results show that the initial mass flux of heptane, $0.0087kg/m^2{\cdot}s$, is increased to $0.166kg/m^2{\cdot}s$ for fire board and $0.019kg/m^2{\cdot}s$ for steel plate. It means that the fire-scenario should be considered with the thermal characteristics of the material properties and geometric shapes of the compartment to predict fire propagation accurately in a compartment space.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.10
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• pp.914-921
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• 2005

In this study, the 1/20 reduced-scale experiment using Froude scaling were conducted to investigate the effect of longitudinal ventilation velocity on the burning rate in tunnel fires. The methanol pool fires with heat release rate ranging from 2.02 kW to 6.15 kW and the n-heptane pool fires with heat release rate ranging from 2.23 kW to 15.6 kW were used. The burning rate of fuel was obtained by measuring the fuel mass at the load cell. The temperature distributions were observed by K-type thermocouples in order to investigate smoke movement. The ventilation velocity in the tested tunnel was controlled by inverter of the wind tunnel. In methanol pool fire, the increase in ventilation velocity reduces the burning rate. On the contrary in n-heptane pool fire, the increase in ventilation velocity induces large burning rate. The reason for above conflicting phenomena lies on the difference of burning rate. In methanol pool fire, the cooling effect outweighs the supply effect of oxygen to fire plume, and in n-heptane pool vice versa.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.465-469
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• 2004

액정 디스플레이의 백라이트 광원으로 냉음극 방전램프(CCFL: Cold Cathode Fluorescent Lamp)가 일반적으로 사용된다 최근 LCD 모니터의 두께는 갈수록 얇아지며, 화면은 넓어지고 있는 대형화 추세이다. 기존의 권선형 변압기를 이용 인버터를 구성하여 멀티램프를 구동하고 있지만 이는 코어나 권선 손실에 의한 효율 저하와 부피나 중량의 증가, 그리고 과열에 의한 화재의 위험성을 가지고 있다. 이러한 문제들을 해결하기 위해 본 논문에서는 압전 변압기를 이용한 멀티램프 구동용 인버터를 설계 지침에 따라 구성하였다. 인버터 하나로 압전변압기를 병렬로 연결하는 방식을 이용하였고, 또한 전류 부담이 적은 외관 전극 형광 램프(EEFL: External Electrode Fluorescent Lamp)를 이용한 멀티램프 구동 방법을 압전 인버터에 적용 가능한지 고찰하였다. 적용한 방식으로는 풀-브리지 (Full-Bridge)회로를 응용하였다.